1. Field of the Invention
The present invention relates to methods for making insensitive enhanced blast explosive molding powders, and more particularly to methods for making metallized energetic molding powder in a non-aqueous environment.
2. Description of Related Art
Energetic molding powder is used extensively as a component of explosives, warheads and similar ordnance components. Energetic molding powders are typically formed from a combination of energetic solids and a plasticized polymer processed in a bulk phase fluid. Often a metal powder is added to energetic molding powders for specific applications. Methods are available to produce energetic molding powders, which contain a metal powder, but the methods are inefficient, and resultant pressed energetic molding powder products have a number of problematic characteristics.
A common method to form a molding powder product, which contains a metal powder, involves a basic two-step process. The first step is performed in an aqueous environment. This process combines an energetic solid and a plasticized polymer in water, as the bulk phase fluid, to form a molding powder. The second step is mechanically blending the molding powder with a metal powder to form the molding powder product. Since the metal powder and, typically aluminum powder, exothermically reacts with water and generates hydrogen gas, the molding powder is made first then blended with the metal powder.
This process, in part, requires a jacketed tank to make the molding powder as well as an additional piece of process equipment, typically, a double-cone blender, to blend, mechanically and separately, the metallic powder. The additional blending step increases the time and cost per batch of product. This process can not be used to make large quantities of molding powder product (or stored for long periods of time) as the molding powder product exhibits settling problems and, typically, aluminum powder stratification results in undesirable density gradients in the explosive loads. Further, the molding powder is typically more sensitive to impact, fraction and electrostatic discharge stimuli, which result from the relatively hard, dense and gritty nature of the mechanically blended metal, such as, aluminum, powder or particles consolidated into the binder during pressing. Therefore, when sheared, the metal particles contribute to the onset of “hot spot” ignition.
A somewhat related method is available to make molding powder involving a hydrolyzable binder to extract nitramine using a bulk multi-component fluid, that is, a non-aqueous carrier fluid, typically, including a fluorocarbon fluid (or fluorinated oil) and ethyl acetate. This process is focused on an environmentally friendly method of making high explosive molding powder using the non-aqueous carrier fluid, which does not generate contaminated waste water, yet the process attempts to uniformly coat the high explosive with a binder in order to minimize batch-to-batch variations. This process does not contemplate combining the molding powder with a metal powder to produce a molding powder product.
Although efforts have been made to produce energetic molding powders, which contain a metal powder, these methods are ineffective, small batch processes. Thus, there is a need for an improved method of making novel and safe enhanced blast explosive molding powder products in large quantities.